Ink jet printer

ABSTRACT

An ink jet printing system which writes on a record medium by expelling droplets of liquid ink from the cavity of a jet head which is reciprocated repetitively along the printing line. A piezoelectric transducer is used to generate ink droplets on demand under control of suitable storage and character generating equipment. Characters are formed by generating dots in a 5 X 7 matrix as the head traverses back and forth. The record medium is stationary during printing and is advanced one row space at the completion of each horizontal row of dots and also one line space at the completion of each row of characters.

United States Patent 1191 Demer Jan. 22, 1974 INK JET PRINTER FrederickM. Demer, Vestal, NY.

International Business Machines Corporation, Armonk, NY.

Filed: Jan. 8, 1973 Appl. No.: 321,890

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 8/1931 Ranger ..346/75X 6/1950Hansel] ..346/75X Primary ExaminerJoseph W. Hartary Attorney, Agent, orFirm-Gerald R. Gugger et a].

[ 57] ABSTRACT An ink jet printing system which writes on a recordmedium by expelling droplets of liquid ink from the cavity of a jet headwhich is reciprocated repetitively along the printing line. Apiezoelectric transducer is used to generate ink droplets on demandunder control of suitable storage and character generating equipment.Characters are formed by generating dots in a 5 X 7 matrix as the headtraverses back and forth. The record medium is stationary duringprinting and is advanced one row space at the completion of eachhorizontal row of dots and also one line space at the completion of eachrow of characters.

7 Claims, 9 Drawing Figures PMENIH] JAN 2 2 M4 FIG. 3

SHEET 3 BF 8 PATENTEDJANZZ 1974 saw u or 8 PATENTEBJANZ? m4 SHEEI 5 BF 8597- HARD COPY 1. TV- LIKE CHARACTER GENERATION UNBLANK PULSE i2O v 2.CHARACTER FORMAT/0N //V 5x7MA7'R/X o, O 0000.. o

| LEVEL-WINDING SCREW 3 MECHA/V/CAL SCAN PROV/OED JET FIG.

PATENIED JAN 2 21974 SHEEI 7 0F 8 INK JET PRINTER BACKGROUND OF THEINVENTION Fluid droplet printing has been known in the prior art asexemplified by the system shown and described in U. S. Pat. No.3,596,275 which issued on July 27, 1971. In systems of the typedescribed in this patent, a jet of writing fluid or ink is caused toissue from a nozzle in the form of a succession of tiny individualdroplets which are directed toward the surface of a record member. Asthe individual droplets are formed, they are given an electrostaticcharge which is a function of the instantaneous value of an input signalwhich is to be recorded. The charged droplets are caused to pass betweena pair of electrostatic deflection plates. A constant high voltagecharge is applied to the deflection plates to produce a constant highvoltage electric field between the two plates. As the charged dropletspass through the electric field, they are deflected from their normalpath by an amount which is a function of the magnitude of the charge oneach of the droplets and in a direction which is a function of thepolarity of the charge on the individual droplets. Each droplet of theink or writing fluid has its own unique charge characteristic fordirecting it to the desired print position on the record member.

It can be understood that systems of the above patented type arerelatively complex, costly, and difiicult to implement. And for someapplications, this type of printer system is neither desirable norrequired. In the present application to be described, it was desired toprovide a low cost and simple printer for the production of a hard copyduplicate of a message selected from those displayed on a CRT terminal.

SUMMARY OF THE INVENTION In the present invention an asynchronous liquidjet printer system is provided which writes on a record medium byexpelling droplets of liquid ink from the cavity of a jet head which isreciprocated repetitively along the printing line by way of a carriagenut and level winding screw means. Attached to the drive shaft of thelevel winding screw is a timing gear from which a magnetic head derivesthe basic synchronization pulses for the jet head electronic drivingcircuits. Liquid ink is fed to the cavity by gravity flow and the backof the cavity is closed with a sealed in piezoelectric metallic diaphramsandwich. This piezoelectric transducer is of the extensional type inwhich motion is generated by applying a voltage to the piezoelectriccrystal in a radial direction. The application of pulses to thetransducer from suitable storage and character generating equipmentresults in the generation of ink droplets on demand.

Characters are formed by generating dots on a X 7 matrix, 5 horizontallyand 7 vertically, as the head traverses back and forth so that printingoccurs in both directions. The record medium is stationary during theactual printing of each row of dots and during the turn around time ofthe jet head at the end of each row, a paper advance solenoid isactuated. At the end of seven of these paper character-row" advancecycles, all of the selected characters for one line have been printedand during an eighth cycle a line space solenoid is actu ated to advancethe paper to the desired position for the top row of dots of the nextcharacter row.

In the present embodiment, printing occurs 40 characters wide whichoccupy a space of 4 inches. The circuitry for driving the printer isaddressable by switches to print selected characters in each of the 40character positions. To test character sequences and format, todemonstrate graphics, and to print selected text an IBM 1 I30 computersystem is attachable to the printer electronics. The 1130 in this casecontrols print-out from punched cards through Fortran using an I 132write statement.

The present system provides a relatively inexpensive liquid jet printerwhich is adapted to duplicate character generation borrowed from anassociated CRT terminal. It also has advantages over other ink jetsystems in that the liquid ink is not pressurized, no drop deflectionsystem is necessary, and no guttering of unused ink is necessary.

It is, then, a primary object of the present invention to provide anovel low cost asynchronous liquid jet printer.

A further object of the present invention is to provide a novel liquidjet printer wherein the liquid ink is not pressurized and no dropdeflection system is necessary.

A still further object of the present invention is to provide a low costliquid jet printer which is adapted for the production of a hard copyduplicate of a message selected from those displayed on a CRT terminal.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention as illustrated inthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showingthe ink jet printer constructed in accordance with the presentinvention.

FIG. 2 is a front elevation view of the machine of FIG. 1 and shows theink jet head and the level winding means.

FIG. 3 is a side elevation view of the right side of the machine of FIG.1 and shows the drive mechanism.

FIG. 4 is a side elevation view of the left side of the machine of FIG.1 and shows the paper advancing mechanism.

FIG. 5 is a diagram illustrating the method of character generation.

FIG. 6 is a diagram illustrating the scan data time and the pulse rate.

FIG. 7 is a schematic diagram of the ink jet.

FIG. 8 is a block diagram of the circuitry for controlling the printer.

FIG. 9 is a perspective view showing the ink jet head and carriageassembly.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, theprinter apparatus of the present invention comprises a base plate 10 towhich is attached the plexiglass side plates 11 and 12. At the back ofthe machine, there is pivotally mounted a hopper 13 which may be used,if desired, to hold a stack of fanfold forms which may be of paper orcard stock. In front of the hopper, there is rotatively mounted in slotscut in the side plates a shaft 14 which carries a supply paper roll 15.In front of the paper roll, a motor 16 is attached to the right sideplate so that there is clearance between the underside of the motor andthe machine base plate. Fastened to the baseplate underneath the motoris a paper guide plate 17 which curves upward at the front of themachine, as shown in FIG. 3. The paper guide plate extends across themachine and directly behind the top portion of it is a platen bar 18which is fastened to the side plates of the machine. Across the top ofthe platen is a slitting bar 19 which has a groove 20 extending acrossthe front of it so that, if desired, a portion of the paper may be slitfrom the roll and removed by running a knife, or the like, along thegroove.

Referring to FIG. 2, at the front of the machine there is a pair ofroller bearings 21 which are rotatable on a shaft 22 fastened on a pairof spring brackets 23. In the paper guide plate, a pair of slots 24 arecut in alignment with the roller bearings and, as shown in FIG. 4, onthe other side of the guide plate there is a shaft 25 journaled in theside plates. Fixed on this shaft is a pair of feed rolls 26 which are inalignment with the slots and which coact with the roller hearings toadvance the paper. Fastened to the inside of the paper guide plate arethree spring fingers 27 which serve to hold the paper against the platenbar 18. To initially feed the paper into printing position, the paper ismanually advanced along the inside of the paper guide plate 17 until itreaches the feed rolls 26 which are then operated to advance the paperthe rest of the way by manually turning the feed roll shaftcounterclockwise by way of the knurled knob 28 fastened on the end ofthe shaft.

To automatically advance the paper when printing is being carried out,the feed roll shaft 25 is connected to a roller-bearing sprag clutch 29which operates to rotate the shaft only in the counterclockwisedirection. A paper advance arm 30 is connected to the feed roll shaft byway of the clutch and the other end of the arm is connected to a pair ofsolenoids 31 and 32 mounted on a support bracket 33. Electroniccircuitry selectively pulses solenoid 31 during character generation toadvance the paper for dot row scanning and solenoid 32 is selectivelypulsed for line spacing between character rows. The increment that thesesolenoids raise the paper advance arm 30 is translated to paper motionby a return spring 34 which returns the arm down against an adjustablestop screw 35 to effect the counterclockwise rotation of the feed rollshaft through the sprag clutch 29. In the present embodiment, solenoid31 produces a paper advance of 0.0l67 inch and solenoid 32 an advance of0.064 inch.

' As shown in FIG. 4, plexiglass cover plates 36 and 37 are provided andfastened on the top of plate 37 is a U- shaped wire member 38 over whichthe paper is fed so that the paper is kept away from the motor tothereby prevent heating of the motor. It should be understood that it isnot necessary to use roll paper and that individually inserted cutsheets can be used. For some applications, the cut sheets may bepreferred such as, for example, when duplicating a message selected froma CRT display.

Referring to FIGS. 1, 2 and 9, the reciprocating ink jet head andcarriage assembly will now be described. Journaled in the side plates atthe front of the machine is a level winding screw 39. The screw isdriven by means of a gear 40 thereon which is connected by a belt 41 toa gear 42 on the shaft 43 of the motor. The motor runs at a synchronousspeed of 1800 rpm moving the jet head 44 bidirectionally across the faceof the I paper by means of a carriage nut 45 riding on the level windingscrew. The level winding screw, similar to that found in fishermansreels, has turn around channels at each end which transfer a pivotfollower 46 riding in the helical grooves to the alternate return grooveof the screw. The follower 46 is captured in the carriage nut 45 whichcarries the jet head 44 by means of a bracket 47. The carriage nut isacted upon by friction and torques induced by a flat spring 48 fastenedbetween the nut and the base of the machine and the nut is preventedfrom turning by engagement of a sliding surface 49 on the nut to asliding surface 50 on top of the paper guide plate. A microswitch 51 atthe left end of the winding screw is actuated by the carriage nut tostart a count for printing, as will be later described. As best seen inFIG. 3, attached to the drive shaft of the level winding screw is a 60tooth timing gear 52 from which a permanent magnetic transducer(variable reluctance) 53 derives the basic synchronization pulses forthe jet head electronic driving circuits.

Referring now to FIG. 7, there is shown the details of the jet head 44.Liquid ink is fed to the cavity 54 by gravity flow and is introduced tothe cavity by 2 curved pipe 55 at the top and the drops are generatedfor printing on demand. The body 56 and nozzle portion 57 are preferablyof teflon due to the fact that teflon resists wetting and therebyresists free bleeding of the jet. The nozzle diameter would typically bein the order of 0.004 inch in diameter.

The back of the cavity is closed with a sealed in piezoelectric metallicdiaphragm sandwich. The disc 58 of this sandwich is typically 3/16 inchin diameter and 0.008 inch in thickness. Fastened central to this disc,by epoxy, is a piezoelectric ceramic wafer 59 which is /8 inch indiameter and 0.008 inch in thickness. This piezoelectric transducer isof the extensional type in which motion in a radial direction isgenerated by applying a voltage to the piezoelectric crystal.Application of a positive pulse produces inward radial motion of thecrystal which buckles the metallic diaphragm inward, in the manner of anoil can diaphragm being pushed inward, and liquid is expelled from thecavity. The application of one pulse produces one droplet of liquid orink. The application of two pulses produces two droplets, etc. As shownin FIG. 9, a metal slide plate 60 is provided on the end of the bracket47. This plate slides across the paper and prevents the end or tip ofthe jet nozzle from contacting the paper.

Referring now to FIGS. 2 and 4, a supply of liquid ink is placed in acontainer 61 mounted on a platform 62 which is vertically adjustable byway of a slide plate 63 and screw 64 so that the height of the containercan be adjusted to control the gravity flow of the ink. An air vent hole65 in the cap of the container prevents an air lock and assists thegravity flow. The ink flows out of the container through a liquid line66 and is directed to a T-connector block 67 fastened at the front ofthe base plate. The loop of flat spring 48 is actually split and the twoends are overlapped and fastened between the block and the base toprovide, in effect, a pair of twin oscillating springs. From theconnector block 67, the ink is directed by way of two balanced liquidlines 68 and 69 upward to another T-connector block 70 which issupported on a mounting plate 71 fastened to the carriage nut 45. Theoscillating springs 48 also serve to support these liquid lines, as wellas the electrical lines to the jet. From the connector block 70, the inkis directed through a liquid line 72 supported in a bracket 73 mountedon the carriage nut and the ink is then directed from line 72 throughthe curved pipe 55 and into the cavity 54 in the jet head 44. The liquidlines 68, 69 and 72 are actually connected to the connector block 70 byway of metering restrictor connectors 74 which comprise little needleinserts. During printing when the jet head assembly is reciprocating,the liquid lines 68 and 69 are also reciprocated and as the headdirection reverses, these lines will bend and act as pumps to causeliquid surges. The purpose of the restrictor connectors is to iron outthese surges so that there will be no bleeding of liquid from the jetonto the paper. Connected to the top of the T-connector block 70 is abubble chamber 75 having an air vent hole 76 on top. This chamberfunctions to prevent the build-up of pressure in the connector block 70and thus prevent liquid surges. The chamber and restrictor connectorsserve as a simple pressure filter system.

The method of character generation is outlined in FIG. 5 with therelative jet head and paper motions shown at the bottom of the chart.Print dots 77 are generated starting at the left side of the paper andas the head traverses to the right. All of the top dots of selectedcharacters are printed in this character row motion. During the turnaround time, the paper advance solenoid 31 is actuated and the spring 34completesthe paper advance for a scan-to-left jet dot generation cycle.All of the second row dots of the selected characters are printed duringthis right to left head motion. A similar turn around cycle set-up andpaper advance now takes place. At the end of seven of these papercharacter row advance cycles, all of the selected characters for oneline have been printed. During an eighth cycle, the line space solenoid32 is actuated and the spring advances the paper one line space. Thefirst scan of the next line of selected characters starts when the headbegins advancing to the right. In each case, the paper advance is atrest during the character jet printing function and printing thus occursin both directions. Typical dimensions of the characters and dot spacingare shown in FIG. 5. In the present embodiment, printing occurs 40characters and the 40 characters occupy a space of 4 inches on a paperwidth of 5 inches. Of course, other dimensional formats could be used.

The 5 X 7 character matrix is used to produce a message 40 characters inline width and 6 lines in length with line density being 6 lines perinch. Character width and spacing are such as to give a characterdensity of 10 characters to the inch. The level winding screw 39 whichactuates the jet head is designed with a lead of one turn per revolutionand, as has been described, directly attached to the screw is the 60tooth emitter or magnetic impulse wheel 52 from which impulses aresensed by the magnetic reluctance pick-up head 53. These impulses arebasic to the control of all of the electronics of the machine, as willbe described.

Since there is a character density of 10 characters to the inch andsince the winding screw moves the jet head laterally one inch during 60impulses, it is seen that with the 5 X 7 dot matrix a character space ofone dot exists between characters in horizontal or line directionspacing. The character and character space increments are 0.1 inches.The vertical dot spacing is made approximately 0.016 inches resulting ina between line spacing of approximately 0.067 inches for a line spacingof 6 lines to the inch. This is shown graphically in FIG. 5 where thecharacters ETO are sketched by dot position. At the bottom of FIG. 5there is shown how 7 horizontal raster mechanical scans of a controlleddot position ink emitter generate these characters. It will be notedthat the first scan is from left to right, the next scan from right toleft, etc. A scan data time and pulse rate for a 4 inch write to theright, turn around, and write to the left cycle is shown in FIG. 6.During R-l, R 2. R-3 and K4, the top line of 10 characters are writtenas the head moves horizontally one inch per turn.

Referring now to the block circuit diagram shown in FIG. 8, the motor16, operating at 1800 rpm, drives the level winding screw 39 and thetiming emitter gear 52 which is a 60 tooth wheel with one tooth removedat the home position. This wheel is adjusted at assembly to have anaxial position on the level winding screw such that the missing emittertooth is registered with the magnetic reluctance pick up head 53 at thefirst level winding screw crossover after left turn around. The jet headis also aligned at assembly to have a common perpendicular axis to thisfirst level winding screw crossover after left turn around. The magneticimpulses are sensed by the head 53 and the impulses are fed to amagnetic emitter amplifier shaper 78. The missing pulse from the missinghome tooth on the emitter wheel is reinserted and identified as a homepulse in this amplifier. The output from amplifier 78 feeds a six stagering counter 79 and this counter, because of the 5 character dotpositions plus the single dot character space, as shown in FIG. 5, givesone character pulse output for each six emitter pulses received. Thecharacter pulses from counter 79 feed an up-down binary counter 80 andthe purpose of this counter is to count the chosen number of charactersper page width, which in the present embodiment is 40. By means to bedescribed, the first dot of the first character will be printed at thefirst scan left level winding screw crossover after left turn around.The up-down counter 80, therefore, counts 40 character positions as thefirst print scan to the right proceeds to completion. At the 40character count, one output of the up-down counter goes down in voltagelevel along a line 81 which signals the read only storage (ROS) enableline in a 5 X 7 matrix character generator 82 resulting in stoppingfurther scan one character generation signals. The jet head is nowcarried into mechanical turn around on the right turn around section ofthe level winding screw. The signal on line 81 to the charactergenerator ROS stays down during the entire turn around time. Meantime,the up-down counter 80 is counting the ten more words generated by the60 tooth emitter wheel in this one revolution turn around. At the end ofthis additional ten character turn around time, the signal on line 81from the up-down counter 80 is brought back up in signal level allowingthe character generator 82 to again operate, this time as scan 2proceeds to the left.

During the operation just described, the up-down counter 80 was alsosending character pulses to a row counter 83. The output of the rowcounter, in the scan from left to right, identified row 1 along anoutput line 84. The output on line 84 goes to a logic block 85 whichcontrols whether the identified scan will print dots from the charactergenerator 82 in a left to right going progression or in a right to leftgoing progression in conjunction with the 5 signal lines, identified asline 86, which leave the ring counter 79 and also enter the logic block85 to identify the five dot times and to selectively gate the storedcharacter out of the character generator 82 along lines, identified asline 87, in the selected left or right progression. As shown in FIG. 5,scan 1 is to be a left to right progression as are scans 3, Sand 7.Similarly, upon right turn around the count in row counter 83 becomeseven and the dot output from the character matrix is in a right to leftprogression during scans 2, 4 and 6. The three output lines from the rowcounter 83 are also shown as inputs to the 5 X 7 character matrixgenerator 82. Also, a branch line 88 from the row counter output line 84feeds a solenoid driver block 89 for raster or inter-character outputspacing at each turn around. The row counter output lines 84, 90 and 91feed an AND block 92 and upon the count of eight rows, one output fromthe AND block signals a solenoid driver block 93 to effect a line space.Because of the mechanical structure of the solenoids 31 and 32, bothsolenoid drivers 89 and 93 are activated at 8 row count with the rastersolenoid 31 aiding the line space solenoid 32 in initiating the largeline spacing.

The output from controls printing logic block 85 is taken to atransducer driver block 94 to pulse the ink jet print head 44. A branchoutput line 95 from the AND-block 92 is taken to the AND section of asingle shot 96 whose purpose is to clear the counters. The clearance ofcounters occurs at the end of row count 8 and the coincidence of a newprint cycle, as follows:

The microswitch or left margin switch 51, located at the left end of thewinding screw and actuated by the jet head carriage nut, is connected tothe latch section of logic AND block 97 and is held after make until themissing tooth home-pulse-signal is received at the first level windingscrew crossover after left turn around. At this time, the output oflogic block 97 enters the AND section of single shot 96 in conjunctionwith the row 8 count signal, described above, and all of the countersare reset to zero and a new count cycle is initiated.

. The foregoing has described how information is read from the charactergenerator 82 by the machine operation and associated electronicscontrolled by the level winding screw pulse emitter wheel.

To select the character positions of a 40 character line buffer 98 thatwill either load that position or deliver that position to the 5 X 7character matrix 82, six lines of address, identified by the line 99,are delivered from the up-down binary counter 80 to common lines,identified as line 100, which connect the 40 character line buffer 98with a laboratory automatic interface unit 101. The line buffercomprises six 4 X 4, 64 bit, read-write random access memories for the40 characters. The interface unit is essentially a digital multiplexerfor channeling out of a suitable computer 102 such as, for example, anIBM 1130. The common lines between the line buffer and the interfaceunit may be disconnected if manual switch loading of the 40 characterline buffer is desired. In this case, the same character will be readout of its respective buffer position to the character matrix 82 as eachbuffer address is received along line 99 to the buffer. In this way,line after line of the same characters stored in the buffer may beprinted. Also, by manually changing switches represented by the block103 feeding the buffer, new characters may be manually entered into thebuffer.

Loading of the 40 character line buffer by the computer occurs undercontrol of the interface unit 101. A line, not shown, leaves the rowcounter 83 bringing a line count of eight along the line 104 into theinterface unit. During the 8 time, the line buffer may be loaded fromthe computer. Under this control, a new set of 40 characters may beloaded at each 8 time or, in other words, on a line by line dynamicbasis as long as data is being received from the computer in 40character line widths.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

1. An ink jet printing system for writing on a record member byexpelling droplets of liquid ink which comprises:

an ink jet head comprising a body member having a cavity with a nozzleportion at one end and a piezoelectric metallic diaphragm sealed at theopposite end;

means for supplying liquid ink to said cavity;

means for reciprocating said jet head back and forth across the front ofthe writing surface of said record member;

storage and character generating circuit means responsive to input datato be printed for pulsing said piezoelectric diaphragm whereby dropletsof ink are expelled from said nozzle to produce rows of dots on therecord member as the head reciprocates back and forth;

counter circuit means for controlling the drive of said storage andcharacter generating circuit means;

transducer means controlled by the mechanical motion of the jet head forproducing synchronization pulses for controlling the drive of saidcounter circuit means;

drive means for spacing said record member;

first means responsive to said counter circuit means for actuating saiddrive means to space the record member at the completion of each row ofdots whereby characters are formed in a dot matrix; and

second means responsive to said counter circuit means for actuating saiddrive means to space the record member at the completion of each row ofcharacters.

2. An ink jet printing system as in claim 1 wherein said liquid ink issupplied to the jet head by gravity 3. An ink jet printing system as inclaim 1 wherein said record member may take the form of a roll strip orindividual cut sheets.

4. An ink jet printing system for writing on a record member byexpelling droplets of liquid ink which comprises:

a rotatable helically grooved level winding screw having turn aroundchannels at each end, said winding screw extending across the writingsurface of the record member and in close proximity thereto;

a carriage nut mounted on said winding screw and having a followerriding in the helical grooves; an ink jet head mounted on said carriagenut, said head comprising a body member having a cavity with a nozzleportion at one end and a piezoelectric metallic diaphragm sealed at theopposite end;

means for supplying liquid ink to said cavity;

means for rotating said winding screw whereby said jet head traversesback and forth across the front of the writing surface of said recordmember;

storage and character generating circuit means responsive to input datato be printed for pulsing said piezolectric diaphragm whereby dropletsof ink are expelled from said nozzle to produce rows of data on therecord member as the head traverses back and forth;

counter circuit means for controlling the drive of said storage andcharacter generating circuit means;

transducer means controlled by the mechanical motion of the jet head forproducing synchronization pulses for controlling the drive of saidcounter circuit means;

drive means for spacing said record member;

first means responsive to said counter circuit means for actuating saiddrive means to space the record member at the completion of each row ofdots whereby characters are formed in a dot matrix; and

second means responsive to said counter circuit means for actuating saiddrive means to space the record member at the completion of each row ofcharacters.

5. An ink jet printing system as in claim 4 wherein said transducermeans comprises a toothed wheel rotatable with said winding screw and amagnetic head for sensing the teeth on said wheel.

6. An ink jet printing system as in claim 4 wherein said drive meanscomprises a one-way clutch and feed roll means adapted to space either aroll strip or individual cut sheets.

7. An ink jet printing system as in claim 4 wherein said liquid inksupply means comprises a vertically adjustable ink container and supplylines for feeding the liquid ink to the jet head by gravity flow

1. An ink jet printing system for writing on a record member byexpelling droplets of liquid ink which comprises: an ink jet headcomprising a body member having a cavity with a nozzle portion at oneend and a piezoelectric - metallic diaphragm sealed at the opposite end;means for supplying liquid ink to said cavity; means for reciprocatingsaid jet head back and forth across the front of the writing surface ofsaid record member; storage and character generating circuit meansresponsive to input data to be printed for pulsing said piezoelectricdiaphragm whereby droplets of ink are expelled from said nozzle toproduce rows of dots on the record member as the head reciprocates backand forth; counter circuit means for controlling the drive of saidstorage and character generating circuit means; transducer meanscontrolled by the mechanical motion of the jet head for producingsynchronization pulses for controlling the drive of said counter circuitmeans; drive means for spacing said record member; first meansresponsive to said counter circuit means for actuating said drive meansto space the record member at the completion of each row of dots wherebycharacters are formed in a dot matrix; and second means responsive tosaid counter circuit means for actuating said drive means to space therecord member at the comPletion of each row of characters.
 2. An ink jetprinting system as in claim 1 wherein said liquid ink is supplied to thejet head by gravity flow.
 3. An ink jet printing system as in claim 1wherein said record member may take the form of a roll strip orindividual cut sheets.
 4. An ink jet printing system for writing on arecord member by expelling droplets of liquid ink which comprises: arotatable helically grooved level winding screw having turn aroundchannels at each end, said winding screw extending across the writingsurface of the record member and in close proximity thereto; a carriagenut mounted on said winding screw and having a follower riding in thehelical grooves; an ink jet head mounted on said carriage nut, said headcomprising a body member having a cavity with a nozzle portion at oneend and a piezoelectric - metallic diaphragm sealed at the opposite end;means for supplying liquid ink to said cavity; means for rotating saidwinding screw whereby said jet head traverses back and forth across thefront of the writing surface of said record member; storage andcharacter generating circuit means responsive to input data to beprinted for pulsing said piezolectric diaphragm whereby droplets of inkare expelled from said nozzle to produce rows of data on the recordmember as the head traverses back and forth; counter circuit means forcontrolling the drive of said storage and character generating circuitmeans; transducer means controlled by the mechanical motion of the jethead for producing synchronization pulses for controlling the drive ofsaid counter circuit means; drive means for spacing said record member;first means responsive to said counter circuit means for actuating saiddrive means to space the record member at the completion of each row ofdots whereby characters are formed in a dot matrix; and second meansresponsive to said counter circuit means for actuating said drive meansto space the record member at the completion of each row of characters.5. An ink jet printing system as in claim 4 wherein said transducermeans comprises a toothed wheel rotatable with said winding screw and amagnetic head for sensing the teeth on said wheel.
 6. An ink jetprinting system as in claim 4 wherein said drive means comprises aone-way clutch and feed roll means adapted to space either a roll stripor individual cut sheets.
 7. An ink jet printing system as in claim 4wherein said liquid ink supply means comprises a vertically adjustableink container and supply lines for feeding the liquid ink to the jethead by gravity flow.